Java 28 to Preview Project Valhalla's Value Classes in March 2027
The upcoming JDK 28 release targets a fundamental shift in Java's object model to optimize memory and performance.
Java is preparing for a significant architectural evolution with the development of JDK 28, scheduled for release in March 2027. The upcoming version is set to introduce a highly anticipated preview of Project Valhalla, marking a pivotal shift in how the Java Virtual Machine (JVM) handles memory and performance.
According to OpenJDK and official project documentation, JDK 28 will serve as the Reference Implementation of version 28 of the Java SE Platform under JSR 403. To oversee this transition, the JDK 28 Expert Group has been formally established. The centerpiece of this release is JEP 401, which introduces Value Classes and Objects as a preview feature. The scale of this integration is immense; reporting from the DEV Community notes that the pull request for Project Valhalla adds more than 197,000 lines of code across 1,816 different files.
The Road to Valhalla
Java currently operates on a rigorous six-month release cycle. Following the Long-Term Support (LTS) release of JDK 25, the ecosystem is progressing through JDK 26 and 27. Project Valhalla has been a multi-year effort aimed at optimizing the JVM's memory layout. By introducing value types, the project seeks to eliminate the performance penalties associated with object indirection, allowing the JVM to store data more efficiently in memory.
Impact on Performance
The introduction of value classes represents a fundamental change to Java's object model. By allowing the JVM to treat specific objects more like primitive types, the language can significantly reduce memory overhead and improve hardware utilization. This shift is expected to provide substantial performance gains, potentially narrowing the efficiency gap between Java and low-level languages such as C++ or C# in high-performance computing environments.
What to Watch
As JDK 28 moves toward its March 2027 launch, developers should monitor the evolution of JEP 401. While the integration of Project Valhalla is a massive undertaking, the current focus remains on the preview phase to gather feedback and refine the implementation. The primary objective for the JDK 28 Expert Group will be ensuring that these deep-seated changes to the object model maintain stability while delivering the promised performance breakthroughs.